1. Field of the Invention
The present invention relates to an image information processing apparatus, and more particularly, to an image information processing apparatus which reads image information by using an image information reading means which reads the image information at a variable reading frequency, and switches between a first reading mode in which the reading frequency is set at a predetermined value and a second reading mode in which the reading frequency value can be varied.
2. Related Background Art
Reading apparatuses for blind persons and/or persons having impaired vision, which apparatuses read image information and output the same as tactile information, specifically as vibration patterns, are known. Among such known reading apparatuses for persons of impaired vision are apparatuses by which images displayed on a CRT (Cathode Ray Tube) display unit can be read as well as images recorded on a recording media such as paper. In those apparatuses, an image reading means comprises an image sensor composed of, for example, a CCD (Charge-Coupled Device) element, and the value of a reading frequency thereof can be varied. This varying of the setting of the frequency is necessary because there are a variety of scanning frequencies of the CRT display units, and therefore, beat noise will appear in an output signal reading the images if the reading frequency does not match to a corresponding scanning frequency of the CRT display unit.
Therefore, such reading apparatuses for persons of impaired vision are constructed to enable a reading mode of a reading means to be switched between a mode for reading images displayed on the CRT display unit and another mode for reading images recorded on a recording media. In the mode for reading the images displayed on the CRT display unit, the setting of the above reading frequency value can be varied. Alternatively, in the mode for reading the images recorded on the recording media, the reading frequency is set to a predetermined value.
Accordingly, in the construction of the prior art reading apparatuses for persons of impaired vision, a changeover switch for switching the above modes, and an input switch for varying a setting of a reading frequency value are provided.
In the reading apparatuses for persons of impaired vision (a power switch and other switches, for example, a switch for checking an output voltage of a battery as a power supply) are also provided in addition to the above two switches. To reduce the size of the reading apparatus for persons of impaired vision and improve the portability thereof, and further, to reduce the cost thereof by reducing the number of circuit elements used therein, preferably the number of switches used is kept as low as possible. Note, the operability of the apparatuses must be nevertheless maintained, regardless of the reduction of the number of switches used.